As a fixing device used for an electrophotographic image forming apparatus such as a copying machine or a printer, there is a device for heating a fixing belt having low heat capacity by an induction current generating coil. In the fixing device using the fixing belt, warm-up time is shortened, electric power at the time of fixing is reduced, and energy is saved. Among fixing devices using fixing belts, there is a fixing device in which an induction current generating coil provided in the inside of a fixing belt heats a nip part of the fixing belt in order to efficiently heat the nip part of the fixing belt.
However, when the induction current generating coil is disposed in the inside of the fixing belt, the induction current generating coil itself becomes the heat capacity. Finally, the induction current generating coil is heated to almost the same temperature as the temperature of the fixing belt. Thus, the energy to heat the induction current generating coil becomes wasted, and there is a fear that the shortening of the warm-up time is prevented.